Short-term growth and biomechanical responses of the temperate seagrass Cymodocea nodosa to CO2 enrichment

Seagrasses are often regarded as climate change 'winners' because they exhibit higher rates of photosynthesis, carbon fixation and growth when exposed to increasing levels of ocean acidification. However, questions remain whether such growth enhancement compromises the biomechanical properties of the plants, altering their vulnerability to structural damage and leaf loss. Here, we investigated the short-term (6 wk) effects of decreasing pH by CO2 enrichment on the growth, morphology and leaf-breaking force of the temperate seagrass Cymodocea nodosa. We found that the plant biomass balance under levels of acidification representative of short-term climate change projections (pH 8.04) was positive and led to an increase in leaf abundance in the shoots. However, we also found that plant biomass balance was negative under levels of acidification experienced presently (pH 8.29) and those projected over the long-term (pH 7.82). Leaf morphology (mean leaf length, thickness and width) was invariant across our imposed acidification gradient, although leaves were slightly stronger under [CO2] representative of short-term climate change. Taken together, these findings indicate that a subtle increase in growth and mechanical resistance of C. nodosa is likely to occur following short-to medium-term changes in ocean chemistry, but that these positive effects are unlikely to be maintained over the longer term. Our study emphasises the need to account for the interdependencies between environmental conditions and variations in multiple aspects of the structure and functioning of seagrass communities when considering the likely consequences of climate change.Mobility Fellowships Programme of the EuroMarine Consortium (European Commission Seventh Framework Programme) [FP7-ENV-2010.2.2.1-3]; Foundation of Science and Technology of Portugal [SFRH/BPD/119344/2016, PTDC/MAR-EST/3223/2014]; Natural Environment Research Council (NERC) through the UK Ocean Acidification Research Programme (UKOARP) [NE/H017445/1]info:eu-repo/semantics/publishedVersio

Snapshot of macroalgae and fish assemblages in temperate reefs in the Southern European Atlantic Ecoregion

Most of the biodiversity studies in the South European Atlantic Shelf ecoregion are limited to shallow subtidal or intertidal habitats, while deeper reef habitats, also of relevant ecological importance, are particularly understudied. Macroalgal communities, associated fauna, and sea surface temperature were studied in deep reefs (25-30 m) at two locations in this ecoregion: Parcel, North of Portugal (41 degrees N), and Tarifa, Southern Spain (35 degrees N). Specifically, algal assemblages were assessed using biomass collection and associated ichthyofauna was assessed using visual census techniques using scuba. Seawater surface temperature was higher (>3 degrees C) in the southern region-Tarifa, compared to the northern region-Parcel. Our survey revealed 18 fish species and 23 algae species. The highest abundance of cold-water species (both macroalgae and fish species) was recorded in Parcel and warm-water species were dominant in Tarifa. In light of climate global trends, both regions might experience biodiversity shifts towards tropicalization. Current knowledge on their biodiversity is imperative to further evaluate potential shifts.info:eu-repo/semantics/publishedVersio

Microplastic retention by marine vegetated canopies: simulations with seagrass meadows in a hydraulic flume

Marine canopies formed by seagrass and other coastal vegetated ecosystems could act as sinks of microplastics for being efficient particle traps. Here we investigated for the first time the occurrence of microplastic retention by marine canopies in a hydraulic flume under unidirectional flow velocities from 2 to 30 cm s-1. We used as model canopy-forming species the seagrass Zostera marina with four canopy shoot density (0, 50, 100, 200 shoots m-2), and we used as microplastic particles industrial pristine pellets with specific densities from 0.90 to 1.34 g cm-3 (polypropylene PP; polystyrene PS; polyamide 6 PA; and polyethylene terephthalate PET). Overall, microplastics particles transported with the flow were retained in the seagrass canopies but not in bare sand. While seagrass canopies retained floating microplastics (PP) only at low velocities (<12 cm s-1) due to a barrier created by the canopy touching the water surface, the retention of sinking particles (PS, PA, PET) occurred across a wider range of flow velocities. Our simulations revealed that less dense sinking particles (PS) might escape from the canopy at high velocities, while denser sinking particles can be trapped in scouring areas created by erosive processes around the eelgrass shoots. Our results show that marine canopies might act as potential barriers or sinks for microplastics at certain bio-physical conditions, with the probability of retention generally increasing with the seagrass shoot density and polymer specific density and decreasing with the flow velocity. We conclude that seagrass meadows, and other aquatic canopy-forming ecosystems, should be prioritized habitats in assessment of microplastic exposure and impact on coastal areas since they may accumulate high concentration of microplastic particles that could affect associated fauna.FCT: UIDB/04326/2020/ SFRH/BPD/119344/2016info:eu-repo/semantics/publishedVersio

First report of charcoal rot, caused by macrophomina phaseolina, on Blueberry in Southwestern Spain

In Europe, Huelva province in Southwestern Spain is the main berry production area. Blueberry(Vaccinium spp.) was introduced during the early 90?s as an addition to strawberry cultivation.From 2011 to 2018, blueberry acreage increased from 777 ha to 3,000 ha. In May 2015 andSeptember 2017, wilted southern highbush blueberry plants (cvs. "Star", "Ventura", and "Legacy")were collected from three orchards located in the Huelva production area (Gibraleón and Moguer).The diseased plants showed drying of foliage and brown discoloration of stems and roots. Root andstem of symptomatic plants were surface sterilized (2 min,1% sodium hypochlorite), rinsed, dried,and plated on potato dextrose agar (PDA). After 7 days at 30º C in the dark, fungal isolatesproduced numerous black, round to ovoid shaped sclerotia with an average diameter of 98 μm(range: 61 to 128 μm). Genomic DNA from a single sclerotium isolate (TOR-872) was extractedfollowing the technique described by Bekesiova et al. (1999). Four DNA regions were amplifiedand sequenced: the exon region of translation elongation factor 1- α (TEF-1 α), β-tubulin (β-TUB),calmodulin (CAL), and the ITS region. TEF-1 α was amplified with the EF1-728F and EF1-986Rprimers (Carbone and Kohn, 1999), the β-TUB with the T1 and T22 primers (O?Donnell andCigelnik, 1997), the CAL with the CAL-228F and CAL-737R primers (Carbone and Kohn, 1999)and the ITS with the ITS5 and ITS4 primers (White et al., 1990). After BLASTing the 4 sequencesagainst the GenBank database, the top hits corresponded to Macrophomina phaseolina with a 99-100% of sequence identity for all cases. Our sequences were submitted to GenBank underAccession numbers: MK447854 (TEF-1 α), MK447918 (β-TUB), MK447823 (CAL) andMK447886 (ITS). Morphological and molecular results confirmed this isolate as M. phaseolina(Holliday and Punithalingam, 1970). In Gibraleón, in 7.87% of nearly dead plants (cv. Ventura)only M. phaseolina was isolated, whereas in Moguer disease incidence was 30, 7, and 2.27% in cvs."Star", "Ventura", and "Legacy", respectively. Inoculum for pathogenicity testing was produced bygrowing isolates TOR-872 and TOR-862 (both from diseased blueberry plants) on PDA. Inaddition, pathogenicity of a M. phaseolina isolate (TOR-102), from a strawberry soil and confirmedas pathogenic to strawberry, was tested because blueberry is usually cultivated in soils wherestrawberry had grown. Six potted blueberry plants (cv. "Star") per isolate were inoculated bysubstrate irrigation with 50 ml of a sclerotia suspension (104 sclerotia/ml) of each isolate. Sixcontrol plants were irrigated with water. Plants were held at 28°C and 40/70% relative humidity(day/night) in a growth chamber with a 16-h photoperiod. Four months after inoculation, themortality of the inoculated plants was 33, 50 and 50% for isolates TOR-862, TOR-872, and TOR-102, respectively. M. phaseolina was reisolated from all dead plants. No symptoms were observedin control plants. Macrophomina phaseolina has been associated with a blight disease on blueberryin Serbia (Popović et al., 2018) but this is the first report of charcoal rot on blueberry in Spain. Theaggressiveness of the strawberry soil isolate was also confirmed on blueberry. In Spain, chemicalfumigation in soil is banned in blueberry production. Thus, blueberry may be grown on fields with a previous history of strawberry production and carry-over of M. phaseolina causing charcoal rot maysignificantly impact crop production.Fil: de los Santos, B.. Ifapa Centro Las Torres; EspañaFil: Aguado, A.. Ifapa Centro Las Torres; EspañaFil: Borrero, C.. Departamento de Ciencias Agroforestales; EspañaFil: Viejobueno, Josefina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucuman-Santiago del Estero. Estación Experimental Agropecuaria Famaillá; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Avilés, M.. Departamento de Ciencias Agroforestales; Españ

Superficial sedimentary stocks and sources of carbon and nitrogen in coastal vegetated assemblages along a flow gradient

Coastal vegetated ecosystems are major organic carbon (OC) and total nitrogen (TN) sinks, but the mechanisms that regulate their spatial variability need to be better understood. Here we assessed how superficial sedimentary OC and TN within intertidal vegetated assemblages (saltmarsh and seagrass) vary along a flow gradient, which is a major driver of sediment grain size, and thus of organic matter (OM) content. A significant relationship between flow current velocity and OC and TN stocks in the seagrass was found, but not in the saltmarsh. OC and TN stocks of the saltmarsh were larger than the seagrass, even though that habitat experiences shorter hydroperiods. Mixing models revealed that OM sources also varied along the flow gradient within the seagrass, but not in the saltmarsh, showing increasing contributions of microphytobenthos (17-32%) and decreasing contributions of POM (45-35%). As well, OM sources varied vertically as microphytobenthos contribution was highest at the higher intertidal saltmarsh (48%), but not POM (39%). Macroalgae, seagrass and saltmarsh showed low contributions. Local trade-offs between flow current velocities, hydroperiod and structural complexity of vegetation must be considered, at both horizontal and vertical (elevation) spatial dimensions, for better estimates of blue carbon and nitrogen in coastal ecosystems.Foundation of Science and Technology of Portugal (FCT) PTDC/MAR-EST/3223/2014 UID/Multi/04326/2013 FCT UID/MAR/00350/2018 SFRH/BPD/119344/2016info:eu-repo/semantics/publishedVersio

Vertical intertidal variation of organic matter stocks and patterns of sediment deposition in a mesotidal coastal wetland

Tidal coastal wetlands, common home to seagrass and salt marshes, are relevant carbon sinks due to their high capacity to accumulate and store organic carbon in their sediments. Recent studies demonstrated that the spatial variability of this organic carbon within the same wetland system can be significant. Some of the environmental drivers of this spatial variability remain understudied and the selection of the most relevant ones can be context dependent. Here we investigated the role of bed elevation, hydrodynamics, and habitat type (salt marsh and seagrass) on the organic matter (OM) net deposition-resuspension rate and superficial sedimentary stocks (top 5 cm) at the tidal wetlands of the Ria Formosa, a mesotidal coastal lagoon in South Portugal. Results showed that two vectors of spatial variation need to be considered to describe the intertidal sedimentary OM stocks: the bed elevation that imposes a decrease of the hydroperiod and thus the change of habitat from the lower seagrass Z. noltei to the upper saltmarsh S. maritimus, and the horizontal spatial variation along the secondary channels of the lagoon that imposes a decrease in the current flow velocity magnitude. The multiple linear regression analyses, using data from 40 sampling points, explained 59% of the variation of the superficial sedimentary stocks of OM in salt marshes and seagrasses of the Ria Formosa lagoon and revealed that stocks generally decrease with elevation, yet with variation among sites and habitats. It was also found that the decrease of the OM net deposition-resuspension rate with bed elevation was exponential. Our study emphasizes the importance of considering multiple environmental drivers and spatial variation for regional estimations of organic matter (and organic carbon) sedimentary stocks in coastal wetlands.info:eu-repo/semantics/publishedVersio

Loss of surficial sedimentary carbon stocks in seagrass meadows subjected to intensive clam harvesting

Seagrass carbon stocks are vulnerable to physical disturbance. We assessed the effect of clam harvesting on the organic carbon (Corg) stocks in surface sediments in four intertidal Zostera noltei meadows on the Iberian Atlantic coast (Spain and Portugal), by comparing undisturbed and harvested areas. We also monitored the spatial cover of the meadows throughout the growing season. Sedimentary Corg content and Corg stocks were about four times lower in intensively harvested areas than in control areas, but there were not differences between areas with low harvesting pressure and control areas. Reductions of 53–85% in sedimentary Corg stocks of Z. noltei meadows were caused by intensive clam harvesting. The effect of intensive clam harvesting on Corg stocks increased throughout the growing season, but the area covered by the seagrass increased from 21 to 37%, suggesting rapid recovery of seagrass canopies and potential recovery of sedimentary Corg stocks.info:eu-repo/semantics/publishedVersio

Variation in flexural, morphological, and biochemical leaf properties of eelgrass (Zostera marina) along the European Atlantic climate regions

Seagrasses need to withstand hydrodynamic forces; therefore, mechanical properties such as flexibility or breaking resistance are beneficial for survival. The co-variation of leaf breaking properties with biochemical traits in seagrasses has been documented, but it is unknown if the same patterns apply to leaf flexural properties. To interpret changes in the ecological function of seagrass ecosystems based on acclimation responses to environmental changes, it is necessary to understand the factors that affect flexural leaf properties. Here, morphological and flexural leaf properties of the perennial type of Zostera marina across different environmental conditions along European Atlantic climate regions are presented together with C:N ratio and neutral detergent fibre content as descriptors of biochemical leaf composition. Eelgrass leaves from cold regions were similar to threefold more elastic and similar to tenfold more flexible, were also narrower (1.7-fold), and contained similar to 1.9-fold higher fibre content than from plants growing in warmer regions. Eelgrass also showed acclimation to local conditions such as seasonality, water depth, and hydrodynamic exposure. Leaves collected from exposed or shallower locations or during winter were more flexible, suggesting an avoidance strategy to hydrodynamic forcing, which is generally higher under those conditions. Flexural rigidity was almost equally controlled by bending modulus (35%) and leaf thickness (37%), indicating functional differences compared to leaf breaking described in the literature. Overall, the findings indicate that Zostera marina has a high flexural plasticity and high acclimation capacity to some climate change effects such as sea level rise and increase in storm frequency and intensity.German Science FoundationGerman Research Foundation (DFG) [PA 2547/1-1]Royal Swedish Academy of Sciences (KVA travel grant)FCT-Foundation for Science and TechnologyPortuguese Foundation for Science and Technology [UID/Multi/04326/2019, SFRH/BPD/119344/2016

Microplastics in commercial bivalves harvested from intertidal seagrasses and sandbanks in the Ria Formosa lagoon, Portugal

Through seafood consumption, microplastic (MP) pollution is potentially threatening human health. Commercial bivalves in particular are a cause of major concern because their filter-feeding activity directly exposes them to MP in the water column and they are then ingested by humans. Here, we provide a quantitative and qualitative baseline data on MP content in the soft tissues of three commercially important bivalves (Ruditapes decussatus, Cerastoderma spp. and Polititapes spp.) collected in Ria Formosa lagoon, southern Portugal. The abundance of MPs (items per soft tissue weight) did not significantly differ among species. On average, R. decussatus exhibited the highest MP abundance (on average, 18.4 +/- 21.9 MP items g(-1) WW), followed by Cerastoderma spp. (11.9 +/- 5.5 MP items g(-1) WW) and Polititapes spp. (10.4 +/- 10.4 MP items g(-1) WW). Overall, 88% of the MPs found were synthetic fibres, the majority of which were blue (52%). Size categories >0.1-1 mm and >1-5 mm were the most common (60% and 34% respectively). The most represented polymers were polyethylene (PE) and polystyrene (PS). The unexpectedly high number of MPs recorded in the three commercially exploited species suggests that this semi-closed lagoon system is experiencing a higher anthropogenic pressure than are open coastal systems.Portuguese Foundation for Science and Technology: PTDC/MAR-EST/3223/2014 IF/01413/2014/CP1217/CT0004 UIDB/04326/2020 SFRH/BPD/119344/2016info:eu-repo/semantics/publishedVersio